Both deals are still under review with U.S. regulators.
In Europe Lafarge and Holcim aim to complete their merger next year, having secured European Union approval, to create the world's biggest cement maker with over $40 billion in annual sales.
However, some other potentially major deals barely got off the drawing board, such as brewer SAB Miller's approach to family-controlled Dutch rival Heineken.
"There is no stigma to deal-jumping any more," said Chris Ventresca, JPMorgan's global co-head of M&A.
"Companies have greater confidence and can withstand a bump in the road because there is less uncertainty on their prospects," he added.
Europeans bidding in America
Expanding abroad has been a key motivator this year for European companies looking to escape from the continent's sluggish economies, with the United States a prime target.
In September Germany's Siemens struck a $7.6 billion all-cash deal to buy U.S.-based Dresser Rand.
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"The largest world economy is open for transactions and is growing in a more predictable way than many other geographies," said Severin Brizay, head of M&A in EMEA at UBS.
At the same time U.S. firms are becoming more cautious about Europe. "They need to see that the economies in Europe are stabilized and going up, but there is not a big consensus on that," said Ventresca.
Some also had to think again after the U.S. Treasury moved to deter so-called "inversion" deals whereby companies were making acquisitions to reincorporate abroad to avoid high taxes at home.
As a result U.S. drugmaker AbbVie pulled the plug on its $55 billion deal to buy Dublin-based Shire, while Pfizer faced a U.K. political backlash against its proposed $118 billion acquisition of AstraZeneca.
However, changes in U.S. tax rules so far have not killed off further inversion deals altogether.
"Companies will always factor in minimizing taxes as they consider the best way to structure their business. That is their job," said Bob Eatroff, co-head of M&A for the Americas at Morgan Stanley.
Meanwhile in Europe the emergence of unexpected but deep-pocketed "left-field" buyers from developing economies has raised the stakes for some prospective Western acquirers, including private equity firms.
Buy-out firms, whose acquisitions accounted for around 8 percent of the M&A market this year, have at times struggled to compete on price.
Chinese buyers had a particularly strong year in Europe, bankers said, targeting Germany's medium-sized manufacturing firms and distressed assets in Southern Europe.
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"China needs M&A to achieve true international expansion, beyond markets such as Brazil or Africa, and a wider access to technology," said Pereira.
With cross-border activity on the rise, the ingredients for another busy year are all there with bankers predicting a new wave of deals in financial services, chemicals and energy as well as continuing consolidation in both healthcare and the telecoms, media and technology (TMT) sector.
"Investors tend to punish idleness," said Lazard Germany's co-head of investment banking, Ken Oliver Fritz.